The present invention is directed to pulse combustion heating apparatus, and more particularly to a pulse combustion heating apparatus having a continuously-variable rate.
A multiple rate pulse combustion burner of the Helmholtz-type is described in U.S. Pat. No. 4,708,635 (Vishwanath), incorporated by reference herein. In this apparatus, a primary burner with a low input rate and a main burner having a higher input rate are combined to provide an integrated combustion process. Vishwanath describes the size ratio between the main and primary burners and states that up to a 100% turn-down (modulation of input rate) of the main burner can be achieved However, Vishwanath does not provide for the control of air flow into either the primary or the main burner, so that the air flow control means is fixed for any given application and is related to the pressure oscillations within the combustor system and the design of the two air flapper valves. Furthermore, in a high-efficiency combination heating/cooling system, the heating portion of the system must possess a high steady-state efficiency and be capable of operating with an input rate having a wide range. Consequently, a pulse combustion burner of the type disclosed by Vishwanath would not be suitable for such a high-efficiency combination heating/cooling system.
It is the solution of this and other problems to which the present invention is directed.